Hermetically sealed packages for electronic components from which connections to those components extend have been comprised of a base having a wall thereon and a cover on the wall. These components are generally made from ceramic material, and the electronic components are mounted in the space between the base and the cover. Terminals from the electronic device extend through apertures in the cover, and hermetic seals are formed between the cover and the wall and between the terminals and the edges of the aperture.
In some applications, the terminals are fairly rigid so that the physical connections of suitably stiff leads thereto can rupture their hermetic seals. Another disadvantage is that the hermetic seals can also be ruptured by thermal expansion of the terminals. Furthermore, the hermetic seals can only be tested after the entire package is completely fabricated so that any leak that may be present can be in any of the many seals.